Schiff bases and metal chelate pigments made therefrom



v United States Patent Oftice a and R is a phenylene radical of the group consisting of: 45

3,132,140 Patented May 5, 1964 metal of the group consisting of copper, zinc, and nickel; and x and y are the same whole numbers and they are either 1 or 2. The nickel complexes of the Schiff bases of Formula 1 are of particular interest as new yellow 5 pigments having high strength, excellent lightfastness, and

superior resistance to bleeding in organic solvents.

The Schiff bases of this invention are produced by the condensation of an aldehyde with a phenylenediamine. V '1 In a preferred embodiment of this invention, two mols of This invention relates to new and useful Schiif bases th aldehyde of 2,4-dihydroxyquinoline, usually known as and to new arlduseful metal complexes of these Schiif 3-formyl-4-hydroxycarbostyril, are condensed with one bases. mol of p.-phenylenedia1nine to give an insoluble yellow Schiff bases or anils are compounds in which both hycompound which is further reacted with a nickel salt, such drogen atoms of the amino group of an aromatic amino as nickel acetate, preferably in a high-boiling polar solvent, are replaced by a divalent organic radical. illustration of a Schitf base is benzylideneaniline which is lightfastness and other pigmentary properties. formed by the condensation of benzaldehyde with aniline For a clearer understanding of the invention, the folas follows: lowing specific examples are given. These examples are H H intended to be merely illustrative of the invention and not i in limitation thereof. Unless otherwise specified, all parts E20 are by weight.

, Example I 9 1 Benzylidencaniline Part A.The reaction carried out in Part A of this example is represented by the equation appearing below wherein 2 mols of 3-formyl-4-hydroxycarbostyri1 are con densed with one mol of p-phenylenediamine:

3,132,140 SCHIFF BASES AND METAL CIELATE PIGMENTS MADE THEREFROM Edward E. Jaife, Union, N.J., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware NoDrawing. Filed May 10, 1961, Ser. No. 108,999

7 Claims. (Cl. 260-440) Equation 1 The present invention is directed to new double Schiff bases of the following structural formula:

FORMULA 1 O H I 0H t V I 2 p in which R is an aromatic radical of the group consisting 0 =C of 2H2O I a on on a \N 0 4.0 and Equation 2 N 37.8 parts (0.2 mol) of 3-formyl-4-hydroxycarbostyril is suspended in 1000 parts of n-butanol to which is then added 108 parts (0.1 mol) of p-phenylenediamine. The mixture is heated to the boil under good agitation and is boiled under reflux for about 4- hours. The first reaction product is the reddish yellow mono-condensation product which is converted on further boiling to a pale greenish yellow product. The slurry is cooled and the product isolated by filtering and washing with ethanol to give parts'(100% yield). A small sample was purified by V i and These new Schiff bases are colored products, and they are intermediates which form colored complexes with such metals as copper, zinc, nickel, and the like, in which there is an average of one metal atom per molecule of the Schiff base. Such complexes may be represented by the following structural formula: I

FORMULA 2 12.44%. Found: C, 69,36%; H, 4.27%, N,

l Part B: Formation of nickel complex.22.5 parts jected to elementary analysis.

Analysis.Calculated for C H N O C, 69.4%; H,

0 parts of dimethylformamide to which is then added 19 parts (0.075 mol) of nickel acetate (Ni(C H O .4H O). The mixture is heated at the boil under reflux for about 3 hours, filtered hot and washed with water until free of H X soluble nickel, Upon drying, there is obtained 25.5 parts in which R and R are the same as in Formula 1; Me is a 5 of theory) of a brilliant yellow product.

A typical 15 to give a highly insoluble yellow compound of excellent extraction with boiling dimethylformamide and then sub- (0.05 mol) of the product of, Part A is dispersed in 750 alkyd a Analysis-Calculated for C H N O Ni Ni, 11.55%; C, 61.6%; H, 3.16%. Found: Ni, 10.8%; C, 60.0%; H, 3.0%.

On the basis of the above analysis and the Schitf base used, the product is considered to have the following structural formula:

FORMULA 3 finlsh which shows excellent lightfastness after 500 hours in an Atlas Fad-O-Meter. ing and completely resistant to bleeding on overstripe tests and in hot paratfin and, in contrast to many prior art chelated pigments, it is stable in acid-catalyzed alkyd resins.

Example II Part A.- The reaction carried out in Part A of this example differs from Example I in that o-phenylenediamine is used in place of p-phenylenediamine. The

OH ffk a r r it 4 V1}; 0 v

=N N= I ll 1 I V1]; :0 T: N

h Equation 3 37.8 parts of 3-formyl-4-hydroxycarbostyril is suspended in 1000 parts of n-butanol to which is then added 10.8 parts of orthophenylenediamine. The mixture is heated to the boil under good agitation and boiled under reflux for about 4 hours. The slurry is cooled and the product isolated by filtering, washing with ethanol and drying to give 41 parts (91% yield) of a yellow solid.

Analysis.Calculated for C H N O N, 12.44%. Found: N, 11.87%.

Part B: Formation of nickel c0mplex.22.5 parts (0.05 mol) of the yellow product of Part A is slurried in 750 parts of dimethylformamide along with 19 parts (0.075 mol) of nickel acetate (Ni(C H O .4H O). The mixture is then heated at the boil under reflux for about 2.5 hours. It is filtered hot and washed free of soluble nickel with water and finally dried to give 24.5

It is heat resistant on bak FORMULA 4 When the metal complex of this example is used in a coating composition, finishes obtained; from such compositions are red shade yellows of excellent lightfastness.

They are non-bleeding in overstripe tests and in hot oils.

Example III PREPARATION OF SOHIFE BASE IN AN AQUEOUS SYSTEM 189 parts of 3-formyl-4-hydroxycarbostyril is suspended in about 4000 parts of water, and the slurry is adjusted to a pH of about 3.0 with H 54 parts of p-phenylenediarnine is then added, the slurry is heated to boil and boiled for about 1 hour. A pale greenish yellow premono-condensation product. condensation product, on treatment with boiling dimethylformamide, readily disproportionates to give the desired Schifl? base plus free phenylene diamine.

As a variation on this process, it is convenient to use a slurry of 3-formyl-4-hydroxycarbostyri1 asobtained by the reaction of 2,4-dihydroxyquinoline with chloroform and sodium hydroxide in an aqueous suspension, without prior isolation of the aldehyde; in which case, an appropriate increase in acid is required to neutralize the alkali present and provision should be made for removing excess chloroform by steam distillation during the reaction period at the boil. 1

Example I V carbostyril is suspended in 650 parts of ethanol along' with 10.8 parts (0.1 mol) of p-phenylenediamine. The

Found: N, 14.8%.

Part B.-The solid from Part A (27.9 parts) is suspended in 800 parts of n-butanol to which 12.2 parts of salicylaldehyde is added and the mixture is boiled under reflux for about 4 hours. It is then cooled, filtered, washed with alcohol and dried to give about 30 parts Part C.-19 parts of the above Schifi base is suspended in 1000 parts of dimethylfiorrnamide along with 19 parts of nickel acetate (Ni(C H O .4I-I O) and the mixture is boiled un er reflux for about 4 hours. It is cooled to 100 C., filtered, washed with alcohol and dried to give 19 parts of a yellow pigment which shows excellent lightfastness on testing an alkyd dispersion for about 375 hours in an Atlas Fade-O-Meter.

Analysis-Percent Ni iound, 12.6%; calculated, 13.4%

The aldehyde, 3-formyl-4-hydroxy-carbostyril, which is used as a starting material in this invention is a known compound which can be conveniently prepared in aqueous media by the well-known Rienuer-Tiermann reaction. In this reaction, 2,4-dihydroxyquinoline (alsoknown as 4-hydroxycarbostyril, and probably existing as a mixture of the keto and enol forms) isreacted with chloroform and a strong alkali such as sodium hydroxide, followed by acidification to liberate the tree aldehyde. It is not essential torecover the aldehyde in dry i'orm. If desired, the phenylenediamine can be added directly to the reaction mixture atter the acidification step and the excess chloroform can be removed by steam distillation during which time the reaction of the aldehyde and the diamine is effected.

The condensation of the aldehyde with the diamine can be carried out in a variety of polar solvents. n-Butanol is shown in the examples, but ethanol, propanol, dimethylforntarnide, ethylene glycol, and the like may be used with equal success. Significantly, it is tound that the reaction proceeds readily in an acidic aqueous medium (pH 3-5) as illustrated in Example 111.

The nickel complexes can be successfully tor-med by reacting the Schifi base with a nickel salt of an organic acid in suspension in high boiling polar solvent such as dimethyliormamide, dimethylacetamide, dimethylsulioxide, tetnamethylene sultone, and the like. Since the condensation to form the Schifi base can also be carried out in a high-boiling polar solvent such as dimethy-lfor-mam- I ide, it is possible and feasible that both the formation of the Schiff base and the metal complex can be carried out in succession in the same reaction medium without intermediate isolation of the Schifi base.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited to said details except as set forth in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A compound of the following structural formula:

O N H consisting of in which R is an aromatic radical selected from the group consisting of r and R is a phenylene radical selectedirom the group 2. A compound of the following structural 5 3. A compound of the following structural formula:

p l p l 4. A compound of the following structural formula:

5 A nickel complex of the formula H V x where x and y are 1-2 and they are the same whole numbers, R is an aromatic radical selected from the group consisting of OH OH and Y O and R is a phenylene radical selected from the group consisting of 6. Anickelcomplexofth formula 7. nickel complex of the formula 1 References Cited in the file of this patent UNITED STATES PATENTS 2,239,290 Krzika11-a et al. Apr. 22, 1941 5, 2,345,485 Krzikalla ef al. l Mar. 28, 1944 

1. A COMPOUND OF THE FOLLOWING STRUCTURAL FORMULA:
 2. A COMPOUND OF THE FOLLOWING STRUCTURAL FORMULA: 